Turnage/Scofield, Barbican Hall, London

The heading may say classical, but this was not just any old classical event. Far from it. Arguably it was mostly a jazz event, though with some strong classical elements. What does that make it? Crossover? Fusion? A bold new genre-transgressing mode of musical discourse? None of the above?

Its origins lie, however, with one of the UK's leading classical composers, Mark-Anthony Turnage, certainly the most acclaimed figure of his generation (he's coming up to 45), and his long-standing and profound love for jazz. Lots of previous classical composers - Ravel, Stravinsky, Milhaud, Weill, Berg - have shown an interest in jazz, though its impact on their music was occasional and relatively superficial. In Gershwin and Bernstein there's a more pervasive strain, and their knowledge of the linguistics of jazz went deeper, finding a stronger echo in some of their works. Pieces like Gershwin's Rhapsody in Blue or An American in Paris utilise a jazz-derived language in the most convincing way yet achieved as transferred to a classical ambience. But Gershwin wasn't writing pure jazz, and wouldn't claim to have done so.

Turnage has been working with leading jazz musicians for a decade now, while his music has paid tribute to figures he particularly admires - such as Miles Davis - for much longer. In Scorched (an acronym for SCofield ORCHestratED), he takes pieces by a guitarist who worked with Davis - John Scofield - and adapts them for something between a classical orchestra and a big band. But these are not mere arrangements - they're more imaginative and interventionist than that - rather they are re-thinkings of Scofield's originals in an alternative medium. It's not that dissimilar, in fact, to what classical composers have already been doing for hundreds of years in variations on other people's themes.

That the results meet the high standards Scofield has the right to respect where his own work is concerned is evident from his participation in the project, here playing on the platform alongside other leading jazz musicians John Patitucci (bass) and Peter Erskine (drums). Their pleasure in their own virtuoso music-making, especially in the neat Scofield trio-settings embedded within the piece, was obvious, and exciting, in their every note. But inevitably there's a good deal of Turnage here, too - in the elemental uproar of the brass writing, the quirks and quiddities of the woodwind, and the dangerously manic tendencies of the strings. The Scottish Chamber Orchestra relished their task on this occasion, playing with a brazen energy and a fervour that approached the Dionysian. Conductor Stefan Asbury held the whole thing together - at least as far as was good for it - and we all had a wonderful time.

Earlier, Scofield, Patitucci and Erskine, joined by saxophonist Joe Lovano, had given us a set of jazz, pure and not so simple, that was rapturously received by an audience including many devotees. But even the one ostensibly "classical" piece on the programme, Turnage's A Man Descending, written for Lovano's many-voiced tenor sax and propounded by him with a troubled eloquence, contains much that is jazz-derived - not least the improvised passages in which Lovano's line soared and swooped in free musical fall. The piece is partly conceived as a homage to Vaughan Williams's ethereal The Lark Ascending, with its unforgettable light-and-heat-haze vision of the English countryside. Turnage's vision is darker, and of the earth, earthy, but no less evocative in its sombre, downwards trajectory.

After these, Scorched - which I'm sure fills a CD very nicely - was too long for a second half, by about three movements, I reckon. But it was a truly remarkable listen, whatever label it comes under.